b

function buy(address _reserveToken, uint256 _depositAmount, uint256 _minimumValue) public returns (uint256 value) {
    uint8 reserveRatio = reserveRatioOf[_reserveToken];
    if (reserveRatio == 0 || _depositAmount == 0) // validate input
        throw;
    if (stage != Stage.Traded) // validate state
        throw;

    ReserveToken reserveToken = ReserveToken(_reserveToken);
    uint256 reserveBalance = reserveToken.balanceOf(this);

    BancorFormula formulaContract = BancorFormula(formula);
    value = formulaContract.calculatePurchaseValue(totalSupply, reserveBalance, reserveRatio, _depositAmount);
    if (value == 0 || value < _minimumValue) // trade gave nothing in return or didn't return a value that meets the minimum requested value
        throw;
    if (totalSupply + value < totalSupply) // supply overflow protection
        throw;
    if (!reserveToken.transferFrom(msg.sender, this, _depositAmount)) // can't withdraw funds from the reserve token
        throw;

    uint256 startSupply = totalSupply;
    totalSupply += value;
    balanceOf[msg.sender] += value;
    dispatchConversion(_reserveToken, msg.sender, true, startSupply, reserveBalance, value, _depositAmount);
    return value;
}